An in vitro model for follicle-associated epithelium will be developed with tissues from rhesus macaques. Rectal crypt epithelial cells will be immortalized by transfection with oncogene constructs (T antigen, or HPV E genes) that are regulated by the villin promoter to increase expression in epithelial cells. Clones will be screened to select ones most similar to crypt cells. The immortalized cells will be grown as monolayers to simulate rectal mucosal epithelium; differentiation of M cells will be promoted by coculture with mucosal lymphocytes. Mucosal lymphoid cell lines will be obtained by H. papio transformation of follicle B cells; T cell lines will be obtained after transformation with H. samirii. This collection of cell lines will be cocultured in vitro to generate a mucosal epithelium that will selectively transport SIV and emulate early events in infection. Future applications will include the study of binding determinants for virus and the evaluation of immunity mechanisms proposed to block intrarectal virus transmission.